U.S. Pat. No. 5,914,884 discloses a method for evaluating the properties of a plastic material in a plastic injection-molding method. An empirical model is used to describe the relationship between process variables and a multiplicity of quality characteristics. The empirical model is produced with reference to empirical data determined by means of a plastic injection-molding process. One of the disadvantages of this method is the practical difficulties and the necessary expenditure involved in the generation of the empirical model.